The electrochemical treatment of large quantities of nanoparticles, including coating, stripping, oxidation, reduction, cleaning, dealloying of nanoparticles and so on, has long been a technical barrier for more extensive applications of this technique, in a range of applications including, but not limited to, fuel cells, batteries, and heterogeneous catalysis. Heretofore treatment of nanoparticles has resulted in extremely non-uniform treatment of the nanoparticles.